Sequence appears to grow quite quickly. Is it always positive?
Source: 2019 Pan-African Shortlist - A5
January 18, 2021
algebraSequencesnumber base
Problem Statement
Let a sequence be defined as follows:
[*] is some positive integer, which can of course be written in base 10.
[*] For if , let be the positive integer whose base- representation is the same as 's base- representation. Then let . If , .
For example, if , then ; ; ; .Does there exist such that is strictly positive for all ?